Sombre Prince Charles joined by William, Harry and Camilla at the funeral of his closest friend Hugh van Cutsem

Prince Charles was joined by his sons William and Harry at the funeral of his closest friend Hugh van Cutsem today.

The Prince of Wales and Camilla, Duchess of Cornwall, were among the mourners attending the service at Brentwood Cathedral in Essex to honour the life of the conservationist who died last week, aged 72.

Dressed in a blue, double-breasted suit, the Prince, and Camilla, wearing a black skirt and jacket, and hat, spent a few moments talking to clergy gathered outside the entrance.

In mourning: The Prince of Wales accompanied by the Duchess of Cornwall, the Duke of Cambridge and Prince Harry arrive at the Cathedral of Saint Mary and Saint Helen in Brentwood, Essex, for the funeral of Hugh van Cutsem

Passed away: Hugh Van Cutsem (left) had known the Prince for more than 50 years, and sources say he and his wife Camilla have taken his death 'hard'

Final tribute: Hugh Van Cutsem's coffin arrives at Brentwood Cathedral ahead of the Requiem Mass this morning

They were then followed into the cathedral by Prince William, dressed in navy, and Prince Harry, in a lighter blue suit.

Shortly afterwards, the coffin was carried into the church by men dressed in tweed suits, with the trousers cropped just below the knee. It was followed by Mr van Custem’s widow Emilie, and his four sons.

Prince Charles and Mr van Cutsem, a former officer in the Household Cavalry, had been close since their days together at Cambridge University and shared passions for rural life, field sports and conservation.

He and his wife were hugely important to not only to Prince Charles, but also his sons.

Chat: The Prince of Wales, the Duchess of Cornwall, the Duke of Cambridge and Prince Harry greet Hugh van Cutsem (right) with his brother William (middle) following the funeral service for their father

Family: The father, his two sons and Camilla chatted for a while before they went their separate ways

Goodbyes: The Prince looked emotional after the service as William and later Harry kissed him and left

Fond farewell: Harry kisses the Duchess of Cornwall after the moving service in Essex today

Prince Charles appeared emotional as he left the funeral of his close friend Hugh van Cutsem today, stopping briefly to speak with clergymen before kissing his sons, William and Harry, goodbye.

The Prince of Wales had attended the requiem mass with his wife, Camilla, the Duchess of Cornwall, flanked by Princes William and Harry.

They were the first to leave Brentwood Cathedral in Essex after Mr van Cutsem's coffin was followed out of the church by his wife Emelie, and four sons.

The private service, led by Rt Revd Thomas McMahon, the Bishop of Brentwood, lasted around 90 minutes.

Each of Mr van Cutsem's four sons, Edward, Hugh, Nicholas and William gave readings during the mass which featured traditional hymns including Pie Jesu sang by the choir.

Cardinal Cormac Murphy-O'Connor, the retired archbishop of Westminster, read the prayer of commendation.

Close: William and Harry are good friends with Mr Van Cutsem's four sons, as the group are roughly the same age

Sons and wives: (front to back) Edward and Lady Tamara, Hugh and Rose, Alice and Nicholas and William and Rosie van Cutsem, file towards the cathedral

Devastated: Mr Van Cutsem's wife Emilie follows her husband into the church

Sad: The Van Cutsems file into the cathedral on a day where they remembered their conservationist father

Prince Charles and his family sat in the front row of the church, where it is thought around 700 people were in attendance.

The van Cutsems’ son, Edward, - the Prince’s godson - was one of the two page boys when Prince Charles and Diana married in 1981.

Thirty years later, at the wedding of William and Kate, their five-year-old granddaughter, Grace, was the flower girl pictured covering her ears during the flypast on the balcony of Buckingham Palace.

William and Harry spent a lot of time with the van Cutsem family as their parents’ marriage broke down, and became close friends with the couple’s four sons, Edward, 40, Hugh, 39, Nicholas, 36, and William, 33.

Friendship: Prince Charles and Hugh van Cutsem became friends more than 50 years ago at Cambridge and were always close

Paying respects: Prince Harry strides into Brentwood Cathedral followed by Prince William who spoke to another mourner

It is thought that one of the four van Cutsem sons will be asked to be a godfather to Prince George.

For several years, Mr and Mrs Van Cutsem were Sandringham neighbours of the royal family as the leaseholders of Anmer Hall, a 10-bedroom Georgian property.

After their lease expired, the van Cutsems moved into a country house on their own estate at Hilborough, near Swaffham in Norfolk.

Event: Mr van Cutsem's wife Emilie before the requiem mass followed by her eldest Edward Van Cutsem and his wife Lady Tamara

Difficult day: Nicholas and Alice Van Cutsem, and William and Rosie van Cutsem, walk to the church

A keen businessman, Mr van Cutsem owned a data storage business and worked as an investment manager at Hambro’s as well as having a number of other business interests.

Kate Middleton is not in attendance, but the Duke and Duchess of Gloucester are also part of the congregation, as is Andrew Parker Bowles. The private Catholic mass is expected to last three hours.

Arrivals: Camilla's former husband Andrew Parker Bowles (left) was at the funeral as was the Duke of Northumberland (right)

Respecful: The Duke and Duchess of Westminster with their daughter Lady Grosvenor